Electronic-photonic devices, also known as optoelectronic devices, comprise a class of electronic devices that are capable of sourcing, controlling, and detecting radiation. Electronic-photonic devices include both electronic and photonic functions. In the semiconductor industry, photonic devices have various applications including intra-chip communication and inter-chip communication. In response to more demanding communication bandwidth, energy consumption, and performance standards, photonic devices are increasingly being integrated with electrical circuits to form a type of electronic-photonic device known as an electronic-photonic integrated circuit.
An example of a photonic device that can be included in an electronic-photonic integrated circuit is an optical waveguide. A conventional optical waveguide includes an inner core formed of a material (e.g., an optical medium) exhibiting a first refractive index, and an outer cladding material exhibiting a second, lower refractive index. Optical waveguides can direct the flow of radiation by way of internal reflection of electromagnetic waves at interfaces between the inner core and the outer cladding material. Optical waveguides permit data to be transmitted by way of radiation rather than electricity. Advantageously, radiation is able to carry data over a wider range of frequencies than electricity, meaning that the bandwidth of radiation is greater than that of electricity.
Optical waveguides often exhibit complex, multidimensional shapes. For example, a so-called “rib waveguide” conventionally includes an inner core exhibiting an at least partially stepped cross-sectional shape that mitigates optical signal losses during use and operation of the rib waveguide. Unfortunately, conventional processes of forming such complex, multidimensional shapes are expensive and time consuming. For example, such conventional methods typically require performing an initial photolithographic process (e.g., including photoresist deposition, masking, photoexposure, development, and material removal) to partially form the inner core, and at least one other photolithographic process (e.g., including additional photoresist deposition, masking, photoexposure, development, and material removal) to complete the formation of the inner core. The initial photolithographic process may form a first portion and/or a first shape of the inner core, and the other photolithographic process may form a second portion and/or a second shape of the inner core.
A need, therefore, exists for new, simple, and cost-efficient methods of forming photonic device structures, such as, for example, a photonic device structure of an electronic device (e.g., an electronic-photonic device, such as an electronic-photonic integrated circuit).